Vane pumps are well-known positive-displacement pumps. A simple vane pump consists of a rotor positioned inside a larger circular cavity. The rotation axis is offset from the axis of the cavity and vanes are allowed to slide into and out of the rotor and seal on all edges. This creates, on one side of the pump, vane chambers that increase in volume. These increasing volume vane chambers are filled with fluid forced in by the inlet pressure. Often this inlet pressure is nothing more than pressure from the atmosphere. On the discharge side of the pump, there are created vane chambers which decrease in volume. This forces fluid out of the pump. Typically, these pumps run at relatively high speeds, and the centrifugal force associated with the rotation is used to hold the vanes against the surface of the interior cavity for sealing. While vane pumps are known to have utility, many suffer from a disadvantageous combination of relatively high cost and relatively low longevity.